Isochronous device communication management

ABSTRACT

Various embodiments of the invention relate to apportioning a total memory bandwidth available for a time period amongst a plurality of bandwidth requests according to a power managed profile. In addition, isochronous data transmission may be appended together and transmitted according to a data transmission policy, wherein the policy may include transmitting the appended isochronous data during an opportunistic data transmission, or during a time identified for transmitting a combined isochronous data transmission, but prior to a time delay compliance limit for isochronous requirements.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.12/814,731, filed Jun. 14, 2010, now issued as U.S. Pat. No. 8,462,811,which application is a Continuation application of U.S. patentapplication Ser. No. 10/699,242, filed Oct. 30, 2003, now issued as U.S.Pat. No. 7,808,895 on Oct. 15, 2010.

FIELD

Communication of isochronous data.

BACKGROUND

Isochronous data is defined as time dependent data that must bedelivered within certain time constraints, but unlike synchronous data,need not be delivered only at specific intervals. In addition,isochronous data is unlike asynchronous data which can be transmitted atrandom intervals. Moreover, isochronous software applications may sendisochronous data to and from sensors and transducers, such as videodisplays, video cameras, audio microphones, audio speakers, and datarepositories or sources such as a memory modules. For example,multimedia streams may require an isochronous transport mechanism toinsure that video data is delivered fast enough to enable each frame tobe displayed at its associated render time. The isochronous transportmechanism may insure that audio data is delivered within timeconstraints necessary to prevent buffer under-runs and audible errors atthe codec and speakers. Therefore, isochronous applications fortransmditting isochronous data to and from isochronous devices requireguaranteed bandwidth and deterministic latency between the isochronoustransmitting and receiving devices

In a power managed profile of a digital electronic system, support ofisochronous applications may require more power than support ofinterrupt driven activity such as asynchronous applications or activityinitiated asynchronously. For example, a laptop computer or a handhelddevice using battery power may be unable to support a power managedprofile to maximize battery life and provide adequate isochronouscommunications for its isochronous devices. Specifically, the laptopcomputer or handheld device may exceed the power managed profile whenpowering components (e.g., such as a processor, memory, processor logicand memory controller, chipset logic for handling device, datacommunication bus, and the isochronous device) as necessary to providethe required guaranteed bandwidth and deterministic latency fortransmitting isochronous data within the time constraints required bythe isochronous devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages will become more thoroughlyapparent from the following detailed description, the set of claims, andaccompanying drawings in which:

FIG. 1 is a block diagram of a isochronous device communication manager,according to one embodiment of the invention.

FIG. 2 is a block diagram of a bandwidth manager for apportioning atotal memory bandwidth amongst a plurality of bandwidth requests.

FIG. 3 is a block diagram of a system for transmitting isochronous databetween isochronous devices and a memory, in accordance with oneembodiment of the invention.

FIG. 4 is a flow diagram of a process for transmitting at least oneisochronous data transmission with another isochronous datatransmission, or during an opportunistic data transmission.

FIG. 5 is a flow diagram for appending isochronous data transmissionsinto a combined data transmission, in accordance with one embodiment ofthe invention.

FIG. 6 is a timing diagram of isochronous data transmissions.

FIG. 7 is a timing diagram of combined isochronous data transmissions,in accordance with one embodiment of the invention

FIG. 8 is a timing diagram of combined isochronous data transmissionsshowing opportunistic isochronous data transmissions, in accordance withone embodiment of the invention.

FIG. 9 is a timing diagram of combined isochronous data transmissionsand opportunistic data transmissions for two isochronous devices, inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION

Various embodiments of the invention relate to apportioning a totalmemory bandwidth available for a time period amongst a plurality ofbandwidth requests according to a power managed profile thus achieving abalance between total power available and the minimum bandwidthrequirements of individual entities. Embodiments also includetransmitting together one or more appended isochronous datatransmissions according to a data transmission policy, wherein the datatransmission policy may include transmitting the appended isochronousdata during an opportunistic data transmission or during a timeidentified for transmitting a combined isochronous data transmission,but prior to a time delay compliance limit of an IsochronousApplication/Device. For example, FIG. 1 is a block diagram of aisochronous device communication manager, according to one embodiment ofthe invention. As shown in FIG. 1, isochronous device communicationmanager 101 includes the following components: power managed profile104, bandwidth manager 103, data transmission manager 102, and datatransmission policy 170.

FIG. 1 shows transmitter 1-155 coupled to first isochronous datatransmission 110 having first isochronous media data 112, and coupled tosecond isochronous data transmission 140 having second isochronous mediadata 142. Similarly, transmitter 2-160 is coupled to transmitter 1-155as well as coupled to opportunistic data transmission 150 havingopportunistic media data 152. According to embodiments media data 112,142, 152, and/or 132 may include digital audio data and/or digital videodata. Furthermore, according to embodiments, transmitter 1-155 ortransmitter 2-160 may represent various software and/or hardwaresufficient to select one or more data transmission packets fortransmitting during a certain time period or slot, such as fortransmitting during a period beginning during a desired time andextending subsequent to that desired time for a period necessary for thetransmission of the one or more data transmissions or packets.Specifically, transmitter 1-155 and/or transmitter 2-160 may be capableof selecting, appending, combining, concatenating, and transmittingisochronous data packets, isochronous media data, synchronous datapackets, synchronous media data, asynchronous data packets, and/orasynchronous media data into combined data transmissions andtransmitting the combined data transmissions when desired (e.g., seeFIG. 5 below).

Transmitter 2-160 is also shown coupled to combined data transmission130 having combined media data 132, which is in turn coupled to dataconduit 150. Data conduit 180 is shown coupled to memory 105. Accordingto embodiments, data conduit 180 may include one or more of a data bus,chipset logic, processor logic, a processor, and other electronichardware and/or software sufficient for providing a channel or conduitfor isochronous data transmission communication (e.g., see FIG. 5below). Moreover, according to embodiments memory 105 may be a pluralityof memory modules including various types of memory, such as randomaccess memory (RAM), double data rate RAM (DDRRAM), DDR2, synchronousdynamic RAM (SDRAM), double data rate synchronous dynamic RAM(DDRSDRAM), static RAM (SRAM), flash memory, as well as other types ofsynchronous and asynchronous memory as appropriate.

As shown in FIG. 1, bandwidth manager 103 may obtain a total memorybandwidth available from a memory or a time period (e.g., such as abandwidth available for memory 105), obtain a plurality of bandwidthrequests for the time period for a plurality of isochronous devices, andapportion at least a portion of the total memory bandwidth amongst theplurality of bandwidth requests according to power managed profile 104.Consequently, data transmission manager 102 may then delay transmissionof the first isochronous data transmission 110 having first isochronousmedia data 112, and append first isochronous data transmission 110 withsecond isochronous data transmission 140 having second isochronous mediadata 142 to be transmitted to or from the same isochronous device, intocombined data transmission 130 having combined media data 132. Thus,combined data transmission 130 may be read from or written to memory 105via data conduit 180. More particularly, data transmission manager 102may control delay of transmission of data, pending of data, andtransmission of data to or from memory via transmitter 1-155 andtransmitter 2-160.

Likewise, data transmission policy 170 may identify a plurality oftransmission time periods during which to transmit a plurality ofcombined isochronous data transmissions (e.g., such as for transmittingfirst and second isochronous data transmissions 110 and 140 as acombined data transmission), and select a time to transmit the combineddata transmission between a time for transmitting an opportunistic datatransmission (e.g., such as opportunistic data transmission 150) and atime for transmitting the combined data transmission (e.g., a scheduledtime for transmitting a combined data transmission having first andsecond isochronous data transmissions 110 and 140 combined). Moreparticularly, opportunistic data transmission 150 may be an asynchronousdata transmission, or a third isochronous data transmission (e.g., suchas a third isochronous data transmission from an isochronous deviceother than the isochronous device that first and second isochronous datatransmissions 110 and 140 are being transmitted to or from).

Note that in accordance with embodiments, any or all of the componentsof isochronous device communication manager 101 such as power managedprofile 104, bandwidth manager 103, data transmission manager 102, datatransmission policy 170, transmitter 1-155 and/or transmitter 2-160 maybe embodied in hardware (e.g., such as firmware, state machines, activecircuitry, hardware logic), separate software modules, and/or may beembedded within one another. For example, any of the componentsidentified above may be a separate software or hardware module (e.g.,such as a software or hardware module existing outside of manager 101 asidentified in FIG. 1) and may be designed to operate together or nottogether with other components identified above. Specifically, forinstance any of the components identified above may be separate softwaremodules, such as part of distinct software applications, sold separatefrom the other components. Likewise, in embodiments, power managedprofile 104 and/or data transmission policy 170 may exist outside ofmanager 101 shown in FIG. 1. Similarly, in embodiments, transmitter1-155 and/or transmitter 2-260 may exist within or be a part of manager101 shown in FIG. 1.

Moreover, embodiments can be implemented as computer software in theform of computer readable code to be executed on a microprocessor. Thus,any or all of power managed profile 104, bandwidth manager 103, datatransmission manager 102, data transmission policy 170, transmitter1-155, and/or transmitter 2-160 may be included in computer softwareembodied in any form of computer program product. A computer programproduct may be a medium configured to store or transport computerreadable code, or a medium in which computer readable code may beembedded. Some examples of computer program products are CD-ROM disks,ROM cards, floppy disks, magnetic tapes, computer hard drives, serverson a network, and flash memory. For instance, embodiments can beimplemented as computer software in the form of computer readable codeexecuted on a computer or processor, or in the form of bytecode classfiles running on such a computer or processor

For example, FIG. 2 is a block diagram of a bandwidth manager forapportioning a total memory bandwidth amongst a plurality of bandwidthrequests. FIG. 2 shows bandwidth manager 103 coupled to power manageprofile 104, processor 340, isochronous devices 330, and memory 105.Processor 340 includes processor status 342, which may include factorslike processor C-states, processor STPCLK# throttling, processor thermalT-states, and processor performance P-states. Moreover, according toembodiments, bandwidth manager 103 may also be coupled to have access tofactors including device power management transition latency, andchipset memory throttling policy. Furthermore, according to embodiments,processor status 342, device power management transitional latency,and/or chipset memory throttling policy may be accessible to powermanaged profile 104.

Isochronous devices 330 include device 1-331, device 2-332, device3-333, and additional devices through device N-339. Isochronous devices330 also includes or may be associated with data rate requirements 350having requirement 1-351, requirement 2-352, requirement 3-353 andadditional requirements through requirement N-359. Likewise isochronousdevices 330 includes or may be associated with bandwidth requests 320having request 1-321, request 2-322, request 3-323 and additionalrequests through request N-329.

Next, memory 105 includes total memory bandwidth 308. According toembodiments, total memory bandwidth 308 may be a total memory bandwidthavailable in a power managed profile such as a profile for a computerrunning on battery power and trying to maximize the life of the battery.Thus, the total memory bandwidth may be dependent on selections andpolicies of a power managed profile, such as those related to powerusage by a processor, RAM memory, hard drive, processor logic, memorycontroller, chipset logic, and data bus use. Moreover, total memorybandwidth 308 may depend on power managed profile 104. In turn, powermanaged profile 104 may have factors described above, be influenced byinterrupt driven asynchronous activity (e.g., unless there is anecessity to perform a task that is not initiated asynchronously such asisochronous data communication) and have a goal of minimizing powerconsumption.

Hence, according to embodiments, bandwidth manager 103 may maintain alist of devices and their associated bandwidth. Thus, a system with atotal memory bandwidth of 1400 Mb/s (Megabits per second Peak Readbandwidth) and 1100 Mb/s (Megabits per second Peak Write bandwidth)operating with Processor Front Side Bus speed/Processor Corespeed/System Memory frequency speeds of 400 Mhz/3 Ghz/200 Double DataRate may manage (e.g., have listed) the following:

1. Graphics/Video—200 Mb/s (Read) and 100 Mb/s (Write) bandwidth

2. Interrupt handling—5 Mb/s (Read) and 2 MB/s (Write) bandwidth

3. Processor non-cache execution—20 Mb/s (Read) and 10 Mb/s (Write)bandwidth

4. USB Isochronous traffic—400 Mb/s (Read) and 100 Mb/s (Write)bandwidth

5. PCI Express Isochronous Traffic—400 Mb/s (Read) and 100 Mb/s (Write)bandwidth

6. Other devices—also may have their tables defined.

According to embodiments, bandwidth manager 103 may be configured toapportion or divide at least a portion of total memory bandwidth 308available for a time period amongst a plurality of bandwidth requestsfor the time period for plurality of isochronous devices 330 andaccording to power managed profile 104. Thus, bandwidth manager 103 maydivide or apportion total memory bandwidth 308 into portions of thetotal memory bandwidth 380, having portion 1-381, portion 2-382, portion3-383, and additional portions through portion N-389. Bandwidth manager103 may then apportion or assign one or more of the portions of thetotal memory bandwidth amongst plurality of bandwidth requests 320 forisochronous devices 330, such as according to power managed profile 104,and/or according to plurality of data rate requirements 350 associatedwith plurality of isochronous devices 330. Note that although data raterequirements 350 and bandwidth request 320 are shown as part ofisochronous devices 330 in FIG. 2, it can be appreciated that the datarate requirements and bandwidth requests need not be located within orgenerated at isochronous devices 330 (e.g., the requirements andrequests may be provided by one or more isochronous applicationsexternal to, but related to isochronous devices 330, shown in FIG. 2).

Therefore, according to embodiments, bandwidth manager 103 may obtaintotal memory bandwidth 308 and plurality of bandwidth requests 320 for aperiod of time (e.g., such as for a fraction of a second, for onesecond, or for more than one second). Then, bandwidth manager 103 mayapportion portions of a total memory bandwidth available for a period oftime such as one second amongst bandwidth request 320 for the sameperiod of time (e.g., for the same one second period) according to powermanaged profile 104, processor status 342, and/or data rate requirements350. Therefore, for example, bandwidth manager 103 may divide totalmemory bandwidth 308 into one or more of portion 1-381 through portionN-389, and satisfy at least two of request 1-321 through request N-329,each with at least one of portion 1-381 through portion N-389. Moreover,according to embodiments bandwidth request 320 and/or data raterequirement 350 may be bandwidth requests and/or data rate requirementsfor isochronous devices 330 (e.g., request 1-321 through request N-329,and requirement 1-351 through requirement N-359, may correspond todevice 1-331 through device N-339).

Bandwidth manager 103 may also be coupled to isochronous devices 330 tomanage data communication between isochronous devices 330 and memory105, such as via a data communication conduit (e.g., such as dataconduit 180 shown in FIG. 1 which may be a data bus coupled betweenmemory 105 and isochronous devices 330). For example, FIG. 3 is a blockdiagram of a system for transmitting isochronous data betweenisochronous devices and a memory, in accordance with one embodiment ofthe invention. FIG. 3 shows isochronous applications 444 on the softwareside of software hardware demarcation line 406. Isochronous applicationsmay be one or more software applications including computer software asdescribed above, running on a computer such as a personal computer, anetwork computer, a client computer, a server computer, a laptopcomputer, a palm or handheld computing device, a cellular telephone, amobile telephone, an electronic planner, a processor, or otherappropriate computing device. Additionally, isochronous applications 444may include one or more software applications for communicating ortransmitting isochronous data between one or more isochronous devicesand a data consumer, target, generator, or provider such as memory 105.

Isochronous applications 444 are shown coupled to or associated withprocessor 340 having processor status 342 across software hardwaredemarcation line 406. Processor 340 is coupled to processor logic andmemory controller 460, which is in turn coupled to memory 105 andchipset logic for handling device 470. Chipset logic for handling device470 is coupled to isochronous devices 330 having data rate requirements350 and bandwidth requests 320. Data bus 450 (e.g., such as a dataconduit according to data conduit 180 described above with respect toFIG. 1) couples isochronous devices 330 to memory 105.

Bandwidth manager 103 is coupled to power managed profile 104, processor340, memory 105, and isochronous devices 330. Isochronous devices 330include isochronous device media sensors and transducers 490, such asvideo and audio media inputs and outputs such as video displays, videocameras, audio microphones, audio speakers, and/or other datarepositories or sources such as memory modules other than memory 105.

Thus, in embodiments, total memory bandwidth 308 available for a timeperiod may be a memory bandwidth available for a period of time selectedor determined depending on processor status 342 and/or power managedprofile 104 as described above with respect to FIGS. 1 and 2. Moreover,data rate requirements 350 may be associated with a plurality of timedelay compliance limits for isochronous devices 330, where isochronousdevices 330 are related to isochronous applications 444 run by processor340. More specifically, data rate requirements 350 may be associatedwith time delay compliance limits related to a computing device user'sperception of media data being communicated by the isochronous devices.For example, a computing device user's perception may be related to atime period or frequency for video and/or audio data being rendered forto the user, or a group of users (e.g., such as by averaging the limitsfor the group) where the limit corresponds to a point at which the useror users are able to perceive an effect on the media played or rendered.More specifically, a user perception limit may be selected or determinedaccording to the video frame rate or audio playback rate at which one ormore users can perceive a degradation, or effect on the data beingdisplayed or played. Thus, video, and/or audio can be displayed orplayed at data rates where errors are not perceived by the user.However, for video or audio played at data rates below the userperception limit the user or users would perceive visible or audibleartifacts resulting from discontinuities in the video or audio databeing displayed or played. Such a discontinuity may be the result, forexample, of a video or audio input or output device transmitting orreceiving isochronous data at a frequency below the data raterequirements associated with the user perception limit.

Furthermore, according to embodiments, data bus 450 may transmitcombined isochronous data transmissions such as combined datatransmission 130, to and from memory 105, such as in accordance withdata transmission policy, (e.g., such as data transmission policy 170,determined based on power managed profile 104, and plurality ofbandwidth request 320). Moreover, bandwidth request 320 may beassociated with data rate requirements 350, such as to provide bandwidthrequests for isochronous devices 330 in order to provide isochronousdata transmissions at a frequency sufficient to meet or exceed data raterequirements 350. In addition, according to embodiments, isochronousdata transmitted between isochronous devices 330 and memory 105 may betransmitted via processor logic and memory controller to memory coupling480, and/or via data bus 450. Thus, combined data transmission, such ascombined data transmission 130, may be read from or written to memory105 as controlled by a processor, such as processor 340 via a conduitincluding chipset device 470, processor logic in memory controller 460and coupling 480, or via a conduit including data bus 450. Likewise,according to embodiments, combined data transmission 130 may includeasynchronous data as well as isochronous data.

For instance, FIG. 4 is a flow diagram of a process for transmitting atleast one isochronous data transmission with another isochronous datatransmission, or during an opportunistic data transmission. At block 205a power managed profile is obtained, such as by power managed profile104 being accessible to bandwidth manager 103. Note that hereinobtaining may be described by a process including determining,identifying, selecting, receiving, or already having data informationand/or a component as described above with respect to FIG. 1. At block210 a total memory bandwidth available is obtained, such as by totalmemory bandwidth 308 for a time period, being available to bandwidthmanager 103. According to embodiments, total memory bandwidth availablemay be obtained by polling memory 105. At block 220 a plurality ofbandwidth requests are obtained, such as by bandwidth requests 320 for atime period, being available to bandwidth manager 103. Similarly, inembodiments, plurality of bandwidth requests may be obtained by polling,such as by polling isochronous devices 330 and/or polling isochronousapplications 444 associated with isochronous devices 330. At block 225through block 230, at least a portion of the total memory bandwidth isapportioned amongst a plurality of bandwidth requests, such as bybandwidth manager 103 apportioning some of portions of the total memorybandwidth 380 amongst one or more of bandwidth request 320 according topower managed profile 104 and plurality of data rate requirements 350associated with isochronous devices 330.

More particularly, at block 225 total memory bandwidth is divided intoportions, such as by bandwidth manager 103 dividing total memorybandwidth 308 into one or more of portion 1-381 through portion N-389.At 230 bandwidth requests are satisfied with portions of the totalmemory bandwidth, such as by bandwidth manager 103 satisfying one ormore of request 1-321 through N-329, each with one or more of portion1-381 through portion N-389. At block 240 a data transmission policy isdetermined, such as by determining data transmission policy 170 based onpower managed profile 104 and bandwidth request 320. For example, thedata transmission policy may manage transmitting at least oneisochronous data transmission during a transmission time of one of anasynchronous data transmission and another isochronous datatransmission; or to manage delaying transmission of a first isochronousdata transmission and combining a first isochronous data transmissionwith a second isochronous data transmission from the same isochronousdevice or application.

At block 250 transmission of a first isochronous data transfer isdelayed, such as by data transmission manager 102 delaying transmissionof first isochronous data transmission 110, having first isochronousmedia data 112 to be transmitted to or from a first isochronous devicesuch as device 1-331 and memory 105. According to one embodiment, firstisochronous data transmission 110 is delayed to be appended to one ormore other isochronous data transmissions from the same isochronousdevice or application. Thus, first isochronous data transmission 110 aswell as second isochronous data transmission 140 may be delayed such asto be combined with a third isochronous data transmission from the sameisochronous device or application, or to be transmitted during anopportunistic data transmission which may be an isochronous datatransmission for another isochronous device or application or which maybe an asynchronous data transmission. Also, according to embodiments,first isochronous data transmission 110 need not be delayed. Forinstance, first isochronous data transmission 110 may be transmittedduring an opportunistic data transmission as described above, prior to atime that would require that first isochronous data transmission 110 bedelayed.

At block 252, a plurality of combined isochronous data transmissionperiods may be identified, such as by data transmission manager 102 ordata transmission policy 170 identifying a set of time periods orfrequency at which to transmit a plurality of combined isochronous datatransmissions having media data from at least two isochronous datatransmissions. For example, according to embodiments, data transmissionpolicy 170 reduces a first frequency of transmission times related totransmitting first isochronous data transmission 110 to a less frequentsecond frequency of transmission times related to transmitting combineddata transmission 130. Specifically, in embodiments, the less frequentsecond frequency may transmit combined data transmissions prior toexpiration of a time delay compliance limit and may or may not requiredelay of one or more isochronous data transmissions between anisochronous device or application and a memory. For example, a frequencyor plurality of transmission time periods may be identified to transmita plurality of combined data transmissions 130 each having at leastfirst isochronous media data 112 and second isochronous media data 142.Moreover, in embodiments, combined media data 132 may include first andsecond isochronous media data 112 and 142. Also, in embodiments,combined data transmission 130 may include opportunistic media data 152as well as isochronous media data (e.g., such as by includingopportunistic media data in combined media data 132).

At block 255 a time to transmit the combined data transmission isselected, such as by data transmission manager 102 or data transmissionpolicy 170 selecting, determining, or obtaining, a time to transmitcombined data transmission 130. For instance, a time to transmit may beselected from a transmission time of an opportunistic data transmissionand a transmission time of one of the plurality of combined isochronousdata transmissions, such as those described above for block 252. Ifcombined isochronous transmission path 256 is selected, the processcontinues to block 270 where the first isochronous data transmission isappended with the second isochronous data transmission into a combinedisochronous data transmission, such as by data transmission manager 102appending first isochronous data transmission 110 having media data 112and second isochronous data transmission 140 having media data 142 toform combined data transmission 130 having combined media data 132according to data transmission policy 170. At block 272 the combinedisochronous data transmission is transmitted, such as by beingtransmitted to or from a first isochronous device or application andmemory 105 via conduit 180 or coupling 480, as described above.

Further, according to embodiments, the combined isochronous datatransmission may be delayed such as to be transmitted during anopportunistic transmission, combined with a third isochronous datatransmission from the same isochronous device or application, or to betransmitted prior to expiration of a time delay compliance limit.Moreover, according to embodiments, the combined isochronous datatransmission, or a single isochronous data transmission, may betransmitted earlier than previously scheduled, such as by transmittingthe combined or single isochronous data transmission prior to the nextidentified combined isochronous data transmission time, or prior toexpiration of a time delay compliance limit. Such a transmission of acombined or single isochronous data transmission may or may not becombined with another data transmission, and/or may or may not betransmitted during an opportunistic transmission or during a combinedisochronous data transmission, as described herein. More specifically,for instance, second isochronous data transmission 140 may betransmitted prior to a time when it would normally be scheduled to betransmitted, such as by transmitting second isochronous datatransmission alone, or combined with another data transmission (1)during an opportunistic data transmission (e.g., such as by combiningsecond isochronous data transmission 140 with opportunistic datatransmission 150 and transmitting those transmissions prior to thecurrent schedule for transmitting second isochronous data transmission140), or (2) during a combined isochronous data transmission, (e.g.,such as combining by combining second isochronous data transmission 140with first isochronous data transmission 110 and transmitting thosetransmissions during a combined isochronous data transmission, prior tothe current scheduled transmission time for second isochronous datatransmission 140).

On the other hand, if at block 255, opportunistic transmission path 257is selected, the process proceeds to block 260 where isochronous datatransmission may be appended into an opportunistic data transmission,such as by data transmission manager 102 appending one or more of firstisochronous data transmission 110, second isochronous data transmission140, and opportunistic data transmission 150 to form combined datatransmission 130 for transmission during an opportunistic asynchronousdata transmission (e.g., which may or may not be opportunistic datatransmission 150) or a third isochronous data transmission (e.g., whichis not an isochronous data transmission for the device or applicationwhich the appended data transmissions are being transmitted to or from).At block 262, the opportunistic data transmission is transmitted, suchas by being transmitted to or from an isochronous device or applicationand memory 105 as described above with respect to block 272. Also,according to embodiments, an opportunistic data transmission may includeone isochronous data transmission that is or is not delayed, may includea second isochronous data transmission that is or is not delayed, andmay be transmitted prior to expiration of a time delay compliance limitas described above.

After block 272 or block 262 the process continues to “A”. Note thatblocks 210 through 272 may be described as reoccurring or cyclicprocesses while block 205 may be described as a standing or persistentcondition. Moreover, according to embodiments, block 252 may beperformed any time after block 240. Also, according to embodiments,blocks 262 and 272 may refer to reading media data of the combined datatransmission from a memory or writing media data of the combined datatransmission to a memory.

FIG. 5 is a flow diagram for appending isochronous data transmissionsinto a combined data transmission, in accordance with one embodiment ofthe invention. FIG. 5 shows a process which may or may not representblocks 255 through 272 of FIG. 4 in embodiments to select a time tocombine isochronous data transmissions into a combined isochronous datatransmission or an opportunistic data transmission and to transmit thecombined or opportunistic transmission. For example, at decision block280 it is determined whether an opportunistic transmission is to occur,such as by data transmission manager 102 determining whetheropportunistic data transmission 150 is going to occur and when. If atblock 280 an opportunistic transmission is not going to occur, theprocess continues to decision block 282 where it is determined if it istime for a combined isochronous data transmission to occur. Moreover, anopportunistic transmission may be scheduled to occur before the nextcombined isochronous data transmission is to occur, and thus may providean opportunity for sending one or more appended isochronous datatransmissions as a combined data transmission to be transmitted prior toexpiration of a time delay compliance limit, with or without requiringdelay of one or more isochronous data transmissions.

If at block 282 it is not time for a combined isochronous datatransmission, the process returns to block 280. If at block 280 it istime for an opportunistic transmission to occur, or if at block 282 itis time for a combined isochronous data transmission to occur, theprocess continues to decision block 284 where it is determined whether aburst isochronous transmission is ready, such as by data transmissionmanager 102 determining whether burst isochronous data transmission 110has or will have sufficient media data at first isochronous media data112 to be transmitted. If at block 284 a first isochronous transmissionis not ready, the process returns to block 280. If a first isochronoustransmission is ready at block 284, the process continues to decisionblock 286 where it is determined whether a second isochronoustransmission is ready to be transmitted, such as by data transmissionmanager 102 determining whether second isochronous data transmission 140has or will have sufficient media data at second isochronous media data142 to be transmitted. If at block 286 a second isochronous transmissionis not ready, the process continues to block 288 where the firstisochronous transmission is transmitted, such as by data transmissionmanager 102 transmitting first isochronous data transmission 110 betweenan isochronous device and memory 105 (e.g., such as by transmittingfirst isochronous data transmission 110 as combined data transmission130). If a second isochronous transmission is ready at block 286 theprocess continues to block 290 where the first isochronous datatransmission is appended to the second isochronous data transmissioninto a combined data transmission, such as by data transmission manager102 combining first and second isochronous data transmissions 110 and140 to form combined data transmission 130. Note that according toembodiments, if a second isochronous transmission is ready at block 286the process may return to block 286 to determine whether a third orsubsequent isochronous transmission is ready, until no more isochronoustransmissions are ready to be transmitted prior to or at the time of theopportunistic transmission or combined isochronous data transmission tooccur, for the isochronous device or application. In this manner, morethan two isochronous transmissions may be appended together andtransmitted during the next transmission time.

At block 292 the combined data transmission is transmitted. After block292 the process returns to block 280. Note that in embodiments, thecombined data transmission may include isochronous data that is to betransmitted during the next combined data transmission, such as when anopportunistic transmission occurs. Therefore, in certain instances, itwill not be necessary to transmit some or all of the data usuallytransmitted during the subsequent combined isochronous data transmissiontime.

Incidentally, since isochronous data transmissions are being combinedand transmitted during combined isochronous data transmission timeswhich are less frequent than the time for transmitting singleisochronous data transmission, power is being saved at block 292 and inFIGS. 1 and 3-5. Specifically, power is saved since it is not necessaryto power a computing device processor, memory, bus, memory controller,chipset logic, transmitters, or other components as frequently totransmit the combined isochronous data transmissions as compared to totransmit each single isochronous data transmission. Similarly, sinceduring an opportunistic transmission time any isochronous datatransmission, combined or not, does not require any substantialadditional powering of the components identified above and beyond thatrequired for the opportunistic transmission, power is saved at block 292and in FIGS. 1 and 3-5.

For example, FIG. 6 shows a timing diagram of isochronous datatransmission. FIG. 6 is a graph of data bits 520 versus time 510 showingisochronous data transmissions 501 through 508 having end data bits 522transmitted at times T-511 through T8-518. Thus, according toembodiments, isochronous data transmissions 501 through 508 may eachinclude media data, such as if isochronous data transmission 501 isfirst isochronous data transmission 110 having first isochronous mediadata 112 of video data from a video camera, and isochronous datatransmission 502 is second isochronous data transmission 140 havingsecond isochronous media data 142 of audio data from the same videocamera.

Next, FIG. 7 shows a timing diagram of combined isochronous datatransmissions, in accordance with one embodiment of the invention. FIG.7 is a graph of data bits 520 versus time 510 showing combined datatransmissions 601 through 603 transmitted during combined isochronousdata transmission times as described above with respect to block 282.For instance, combined isochronous data transmission 601 may be combineddata transmission 130 having first isochronous data transmission 110appended to second isochronous data transmission 140 and transmitted atcombined isochronous data transmission time T_(C)-612 prior toexpiration of time delay compliance limit time T_(TD)-619. Also, asshown in FIG. 7, combined isochronous data transmission 601 includesisochronous data transmissions 501 and 502, and has 2N data bits 524 ofdata. Moreover, according to embodiments, combined isochronous datatransmission 601 may represent a “clubbing”, concatenation, appending,combining of data at end points, and/or burst of combined isochronousdata transmissions. For example, combined isochronous data transmission601 may include isochronous data transmission 501 having a first frame,sequence number, header, data field (e.g., between 0 and 4 kilobytes insize), Link Cyclic Redundancy Check (LCRC), and frame to which isappended isochronous data transmission 502 having a second frame,sequence number, header, data field, LCRC, and frame to form a combineddata transmission. Specifically, in the combined data transmission, bothisochronous data transmissions 501 and 502 keep their associated headerin order to guarantee the quality of service (QOS) for each of them.Thus, in the example above, the isochronous data transmissions presentthe data in a serialized manner instead of modifying the data.

Also note that the transmission time of the combined isochronous dataoccurs prior to the expiration of time delay compliance time limitT_(TD). Thus, the isochronous device and/or isochronous application,consuming, displaying, playing, or using the data, such as to projectthe data to a device user, will be able to project the data withoutdegradation to or effecting the user's perception of the data, asdescribed above. For instance, as long as isochronous data transmission502 is ready, combined isochronous data transmission 601 may betransmitted at any time between T1-511 (e.g., when isochronous datatransmission 501 is ready for transmission) and T_(TD)-619 (e.g., theexpiration of the time delay compliant limit). Thus, the time betweenT1-511 and T_(TD)-619 defines a time slot or period during which allisochronous data available at any time during that time slot may betransmitted as a combined data transmission for a specific isochronousdevice or application. More particularly, isochronous data transmission501 may be combined with a second isochronous data transmission from thesame device or application and transmitted (1) at a time that a thirdisochronous data transmission from the same device or application isready for transmission, (2) at a time that an isochronous device from adifferent device or application is ready from transmission, or (3) at atime when a non-isochronous data transmission is ready for transmission,prior to time delay compliance limit time T_(TD)-619.

For instance, FIG. 8 is a timing diagram of combined isochronous datatransmissions showing opportunistic isochronous data transmissions, inaccordance with one embodiment of the invention. FIG. 8 is a graph ofdata bits 520 versus time 510 showing isochronous data transmission 505transmitted as opportunistic data transmission 701 at opportunistictransmission time T_(OPP) 1-711. FIG. 8 also shows opportunistic datatransmission 702 having isochronous data transmissions 507 and 508transmitted during second opportunistic data transmission time T_(OPP)2-712. According to embodiments, opportunistic data transmission 701corresponds to a situation where a first isochronous data transmissionis ready for transmission during opportunistic transmission time T_(OPP)1, but a second isochronous transmission is not yet ready (e.g.,isochronous data transmission 505 is ready, yet isochronous datatransmission 506 is not). On the other hand, according to embodiments,opportunistic data transmission 702 corresponds to a situation where twoisochronous transmissions are ready to be transmitted at theopportunistic transmission time (e.g., isochronous data transmissions507 and 508 are both ready at T_(OPP) 2).

Finally, FIG. 9 is a timing diagram of combined isochronous datatransmissions and opportunistic data transmissions for two isochronousdevices, in accordance with an embodiment of the invention. FIG. 9 is agraph of bus data bits 820 versus time 510 showing combined isochronousdata transmissions for more than one isochronous device or application,and having variously sized data bit transmissions. For example, at timeT1-511, a combined data transmission including isochronous datatransmission 501 having N data bits 822 from a video camera, appendedwith isochronous data transmission 802 having M data bits from the samevideo camera, is transmitted to a memory. Then, at time T2-512, acombined isochronous data transmission having isochronous datatransmission 831 having L data bits 820 from a microphone, appended withisochronous data transmission 832 having N data bits from the samemicrophone, is transmitted to the memory. Note that at opportunistictransmission time T₀₁, that combined isochronous data transmission forthe video camera having isochronous data transmissions 505 and 806 isappended with combined isochronous data transmission for the microphonehaving isochronous data transmissions 835 and 836 (e.g., isochronousdata transmissions 505, 806, 835, and 836 were all ready fortransmission at time T₀₁-815). Subsequently, since all of theisochronous data transmissions prior to time T7-517 are transmitted attime T₀₁, it is not necessary for further isochronous data to betransmitted prior to T7 for the video camera or microphone.

As can be seen from FIGS. 7-9, the number of times data must betransmitted and power consumed in order to transmit that data is reducedas compared to FIG. 6, since the components necessary to transmit thedata need to be powered up less frequently than the eight times theyneed to be powered up in FIG. 6 (e.g., the length of time the componentsare required to be powered up in order to transmit the combined datatransmissions requires less power than is required to power up thosecomponents multiple times for required durations in order to provideseparate transmission of the isochronous data during the eight separatetransmissions).

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. However, it will be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention as setforth in the claims. The specification and drawings are, accordingly, tobe regarded in an illustrative rather than a restrictive sense.

What is claimed is:
 1. A method in a computer system comprising:apportioning at least a portion of a total memory bandwidth availablefor a time period amongst a plurality of digital video data or digitalaudio data bandwidth requests for the time period for a plurality ofisochronous devices, according to a power managed profile, whereinapportioning includes dividing the total memory bandwidth into aplurality of portions of the total memory bandwidth; determining when tocombine data of at least two isochronous data packet transmissions ofdigital video data or digital audio data into a combined data packettransmission, based on the power managed profile; satisfying at leasttwo of the plurality of bandwidth requests each with at least one of theplurality of portions of the total memory bandwidth by appendingendpoints of the data of the at least two isochronous data packettransmissions to form the combined data packet transmission.
 2. Themethod of claim 1, wherein apportioning comprises apportioning the atleast a portion of the total memory bandwidth available according to aplurality of data rate requirements associated with the plurality ofisochronous devices, wherein the power managed profile causes the totalbandwidth to be apportioned amongst the plurality of bandwidth requestsbased at least on interrupt driven asynchronous activity and isochronousdata communication.
 3. The method of claim 1, wherein the combined datapacket transmission is a single databurst transmission during a singletime of data of the at least two isochronous data packets appended atendpoints of the data, wherein obtaining a plurality of bandwidthrequests includes polling a plurality of isochronous applicationscorresponding to the plurality of isochronous devices.
 4. The method ofclaim 1, further comprising: storing the combined data packet in amemory; determining a data transmission policy based on the powermanaged profile and the plurality of bandwidth requests, the datatransmission policy to manage delaying transmission of a firstisochronous data transmission and to manage combining data of the firstisochronous data packet transmission with data of a second data packettransmission into a combined data packet transmission, and to managedetermining when to transmit the combined data packet transmission;after storing, powering-up components required to transmit the combineddata packet; then transmitting the stored combined data packet; andsaving power by delaying transmission of the first isochronous datatransmission and reducing the number of isochronous data transmissionsto satisfy the data transmission policy.
 5. The method of claim 1further comprising: delaying transmission of a third and of a fourthisochronous data packet transmission, and combining data of the thirdand fourth isochronous data packet transmissions with data of anasynchronous data packet transmission into the combined data packet fortransmission.
 6. The method of claim 1, wherein the power managedprofile comprises power usage policies for a processor, RAM memory, harddrive, processor logic, memory controller, chipset logic and data bususe, and wherein the power managed profile apportions the bandwidthbased on a balance between a total power available and a minimumbandwidth requirement of individual entities submitting the requests andincluding the isochronous devices, and wherein apportioning includesdividing the total memory bandwidth into at least four portions of thetotal memory bandwidth to balance between total power availableaccording to the power managed profile and a plurality of minimumbandwidth requirements of individual entities generating the pluralityof bandwidth requests.
 7. A method in a computer system comprising:appending endpoints of data of a first isochronous data packettransmission having media data of digital video data or digital audiodata to be transmitted to or from a first isochronous device with asecond isochronous data packet transmission having media data of digitalvideo data or digital audio data to be transmitted to or from the firstisochronous device into a combined data packet transmission, wherein thecombined data packet transmission is a single databurst transmissionduring a single time, wherein appending is performed according to a datatransmission policy, wherein the data transmission policy reduces afirst frequency of transmission times related to transmitting the firstisochronous data packet transmission to a less frequent second frequencyof transmission times related to transmitting the combined data packettransmission; using the transmission policy to identify a transmissiontime period during which to transmit the combined isochronous datapacket transmission.
 8. The method of claim 7, further comprising:determining when to delay transmission of the first isochronous datatransmission based on the data transmission policy; delayingtransmission of the first isochronous data transmission.
 9. The methodof claim 7, further comprising: using the transmission policy toidentify a plurality of transmission time periods during which totransmit a plurality of combined isochronous data packet transmissions,each combined isochronous data packet transmission having media datafrom at least two isochronous data packet transmissions.
 10. The methodof claim 7 further comprising: using the transmission policy to select atime to transmit the combined data packet transmission, whereinselecting includes selecting between a transmission time of anopportunistic data transmission and a transmission time of a combinedisochronous data packet transmission; and one of reading media datapacket of the combined data packet transmission from a memory andwriting media data of the combined data packet transmission to a memory.11. The method of claim 7, further comprising: determining when toappend the first isochronous data packet transmission with the secondisochronous data packet transmission into a combined data packettransmission, based on the data transmission policy.
 12. The method ofclaim 7, further comprising: delaying transmission of the secondisochronous data packet transmission, and wherein appending furthercomprises: appending an asynchronous data packet transmission with thefirst and second isochronous data packet transmissions to form thecombined data packet transmission into the combined data packet fortransmission.
 13. The method of claim 7 further comprising: the datatransmission policy to manage delaying transmission of a third and of afourth isochronous data packet transmission, and to manage combiningdata of the third and fourth isochronous data packet transmissions withdata of an asynchronous data packet transmission into the combined datapacket for transmission.
 14. A device comprising: a bandwidth manager ofa computer system configured to: apportion at least a portion of a totalmemory bandwidth available for a time period amongst a plurality ofdigital video data or digital audio data bandwidth requests for the timeperiod for a plurality of isochronous devices, according to a powermanaged profile, wherein apportioning includes dividing the total memorybandwidth into a plurality of portions of the total memory bandwidth;determine when to combine data of at least two isochronous data packettransmissions of digital video data or digital audio data into acombined data packet transmission, based on the power managed profile;and satisfy at least two of the plurality of bandwidth requests eachwith at least one of the plurality of portions of the total memorybandwidth by appending endpoints of the data of the at least twoisochronous data packet transmissions to form the combined data packettransmission.
 15. The device of claim 14, wherein the combined datapacket transmission is a single databurst transmission during a singletime of data of the at least two isochronous data packets appended atendpoints of the data, wherein the plurality of isochronous devices arerelated to the plurality of isochronous applications run by a processor,and wherein the data rate requirements are associated with a pluralityof time delay compliance limits for the plurality of isochronousdevices.
 16. The device of claim 14, wherein the combined data packettransmission is a single databurst transmission during a single time ofdata of the at least two isochronous data packets appended at endpointsof the data, wherein the plurality of isochronous devices are related tothe plurality of isochronous applications run by a processor, andwherein the data rate requirements are associated with a plurality oftime delay compliance limits for the plurality of isochronous devices.17. The device of claim 14, wherein the bandwidth manager is coupled tothe plurality of isochronous devices to manage data communicationbetween the plurality of isochronous devices and a memory, and wherein aduration of the time period depends on a status of a processor.
 18. Thedevice of claim 14, wherein the bandwidth manager is coupled to theplurality of isochronous devices to manage data communication betweenthe plurality of isochronous devices and a memory, and wherein aduration of the time period depends on a status of a processor.
 19. Anarticle of manufacture of a computer system comprising: a non-transitorymachine-readable medium having data therein which when accessed by aprocessor causes a bandwidth manager to: apportion at least a portion ofa total memory bandwidth available for a time period amongst a pluralityof digital video data or digital audio data bandwidth requests for thetime period for a plurality of isochronous devices, according to a powermanaged profile, wherein apportioning includes dividing the total memorybandwidth into a plurality of portions of the total memory bandwidth;determine when to combine data of at least two isochronous data packettransmissions of digital video data or digital audio data into acombined data packet transmission, based on the power managed profile;and satisfy at least two of the plurality of bandwidth requests eachwith at least one of the plurality of portions of the total memorybandwidth by appending endpoints of the data of the at least twoisochronous data packet transmissions to form the combined data packettransmission.
 20. The article of manufacture of claim 19, furthercomprising: data to cause the bandwidth manager to determine the datatransmission policy based on the power managed profile and the pluralityof bandwidth requests, the data transmission policy to delaytransmission of a first isochronous data transmission and to combinedata of the first isochronous data transmission with data of a seconddata transmission into a combined data transmission, and wherein thebandwidth manager is configured to save power by delaying transmissionof the first isochronous data transmission and reducing the number ofisochronous data transmissions to satisfy the data transmission policy.21. The article of manufacture of claim 19, wherein obtaining aplurality of bandwidth requests includes polling a plurality ofisochronous applications corresponding to the plurality of isochronousdevices, and wherein the combined data packet transmission is a singledataburst transmission during a single time of data of the at least twoisochronous data packets appended at endpoints of the data; and furthercomprising data to cause the bandwidth manager to: determine when totransmit the combined data packet transmission according to the datatransmission policy, and wherein the power managed profile is based onmaximizing the life of a battery of a computer.
 22. The article ofmanufacture of claim 19, further comprising: data to cause the bandwidthmanager to manage delaying transmission of a third and of a fourthisochronous data packet transmission, and to manage combining data ofthe third and fourth isochronous data packet transmissions with data ofan asynchronous data packet transmission into the combined data packetfor transmission.
 23. A device comprising: a bandwidth manager of acomputer system configured to: apportion at least a portion of a totalmemory bandwidth available for a time period amongst a plurality ofdigital video data or digital audio data bandwidth requests for the timeperiod for a plurality of isochronous devices, according to a powermanaged profile, wherein apportioning includes dividing the totalandwidth into a plurality of portions of the total memory bandwidth;determine when to combine data of at least two isochronous data packettransmissions of digital video data or digital audio data into acombined data packet transmission, based on the power managed profile;and satisfy at least two of the plurality of bandwidth requests eachwith at least one of the plurality of portions of the total memorybandwidth by appending endpoints of the data of the at least twoisochronous data packet transmissions to form the combined data packettransmission.
 24. A device comprising: a bandwidth manager of a computersystem configured to: apportion at least a portion of a total memorybandwidth available for a time period amongst a plurality of digitaldata bandwidth requests for the time period for a plurality ofisochronous devices, according to a power managed profile, whereinapportioning includes dividing the total memory bandwidth into aplurality of portions of the total memory bandwidth; determine when tocombine data of at least two isochronous data packet transmissions ofdigital data into a combined data packet transmission, based on thepower managed profile; and satisfy at least two of the plurality ofbandwidth requests each with at least one of the plurality of portionsof the total memory bandwidth by appending endpoints of the data of theat least two isochronous data packet transmissions to form the combineddata packet transmission.